1. Field of the Invention
This invention relates, in general, to chimney cleaning apparatus, and in particular to apparatus for cleaning prefabricated chimney flues.
2. Description of the Prior Art
The recent proliferation of airtight woodburning stoves having prefabricated metal chimneys has given rise to significant problems relating to chimney cleaning. Wood fuels, unlike oil, coal, or coke, contain large amounts of sap and wood tars which create creosote as the wood burns. Efficient airtight wood stoves tend to produce large amounts of creosote because of long smoldering, flameless, burning. The metal prefabricated chimneys, which are often used in combination with the airtight wood stoves because they provide efficient heat transfer from the gases going to the chimney to the interior of the house, also provide an effective condensing system for the creosote. Creosote, unlike carbon which also accumulates in all chimneys with all types of fuels, ignites readily and once ignited burns intensely and can in turn ignite the carbon. For these reasons, the proliferation of airtight wood stoves used in combination with metal prefabricated chimneys has led to a great increase of chimney fires in the United States, with over 40,000 reported in 1976 alone.
In addition, it is necessary to clean prefabricated metal chimneys often since the accumulation of creosote and soot on the interior of the chimney significantly decreases the heat conductivity through the chimney and thus reduces the efficiency of the heating system. Thus, there is an inherent need for a chimney cleaning device which is readily available and easy to use so that prefabricated chimneys used with airtight woodburning stoves will be cleaned effectively and often.
Early efforts at providing apparatus for cleaning chimneys are typified by U.S. Pat. No. 598,672 issued to P. C. Dunn. Dunn utilized a cable threaded over a pulley to which a brush was attached. A heavy weight was attached to the bottom of the brush to prevent hangup of the brush during its descent. A horizontal drum, to which one end of the cable was attached, was used to return the brush and weight to the top of the chimney. Because of brush hangup problems, brush centering problems, and accidental detachment of the cable from the takeup spool, further inventions to correct these deficiencies were brought about. J. J. Steiner, U.S. Pat. No. 1,184,784, discloses a chain and sprocket wheel system which, while being effective at preventing brush hangup and cable displacement, presents enormous repair problems because of the extreme number of linkages involved, compounded by expansion contraction problems. Additionally, the chain system is too heavy for the modern prefabricated flues currently in use and cost of such chains is prohibitive. U.S. Pat. No. 1,297,090 issued to C. Campbell and J. A. Cameron discloses a double drummed winch, one drum acting as a takeup spool and the other drum acting as a cable release spool. Unevenness in the takeup windings results in slackness of the cable and ineffective cleaning of the flue. Accidental cable displacement is also a problem with the Campbell device. U.S. Pat. No. 1,859,166 to A. Premro discloses a pulley having retaining fingers to prevent accidental displacement of the cable from the pulley. It has been found that a simple pulley, acting as a rotation drum, does not work satisfactorily because of slippage of the cable upon the pulley with a resultant hangup of the cleaning brush.